Method for automatically compensating for unbalance correction position and correction amount in balancing machine

ABSTRACT

Disclosed is a method for automatically compensating for an unbalance correction position and an unbalance correction amount in a balancing machine. The method involves an unbalance testing procedure, an initial unbalance amount determining procedure, a counting procedure, a good-quality determining procedure, an angular deviation measuring procedure, an angular deviation range determining procedure, and an unbalance correction position and amount compensating procedure in order to automatically compensate for the unbalance correction position and amount of a rotor, based on the unbalance correction amount of a previously-corrected thereby achieving an optimum unbalance correction in spite of the fact that there may be errors in unbalance correction position and amount. The automatic compensation method further involves a correction amount re-setting procedure, a current condition displaying procedure, a procedure for automatically stopping the balancing machine, a basic data storing procedure, and an automatic basic data recovering procedure.

TECHNICAL FIELD

The present invention relates to a method for automatically compensatingfor an unbalance correction position and correction amount in abalancing machine, and more particularly to a method for automaticallycompensating for an unbalance correction position and correction amountin a balancing machine, which is capable of greatly reducing the rate ofproducts, for example, rotors, having a poor quality due to an erroneousunbalance correction, while achieving a great improvement inproductivity.

BACKGROUND ART

Generally, a rotor such as an armature, which rotates about an axis, canbe avoided from vibrating during its rotation only under the conditionin which the mass of the rotor is uniformly distributed around the axis.In such a rotor, however, there is weight unbalance, that is, anunbalanced portion, with respect to the axis of the rotor due to variousreasons such as machining errors, and unbalanced molecular arrangement.

Since such an unbalanced portion causes the rotor to vibrate, it isnecessary to make the center of weight of the rotor coincide with theaxis of the rotor by appropriately eliminating the unbalance amount ofthe unbalanced portion, that is, appropriately increasing or reducingthe weight of the unbalanced portion. In this connection, balancingmachines have been proposed. Balancing machine is an apparatus fordetecting the unbalance position and unbalance amount of a rotor, andcorrecting the unbalance of the rotor based on the detected result,thereby making the center of weight of the rotor coincide with the axisof the rotor. Such a balancing machine operates in an additivecorrection fashion or in a subtractive correction fashion in accordancewith an unbalance correction method used therein. In accordance with theadditive correction fashion, a desired balance is obtained by adding aweight to a smaller mass portion. In accordance with the subtractivecorrection fashion, a desired balance is obtained by cutting a desiredamount from a lager mass-portion.

The configuration of a balancing machine operating to perform asubtractive unbalance correction will now be described in conjunctionwith an armature with reference to FIGS. 1 a to 2 b.

FIGS. 1 a and 1 b are perspective views respectively illustratinggeneral armatures. FIG. 2 a is a plan view illustrating a conventional6-axis armature balancing machine. FIG. 2 b is a plan view illustratinga conventional 2-axis armature balancing machine. In FIGS. 1 a to 2 b,identical elements are denoted by the same reference numeral in order toavoid a repeated description thereof.

First, the configuration of the general armature will be described withreference to FIGS. 1 a and 1 b. The armature, which is denoted by thereference numeral 1, includes a shaft 2, a laminated core 3 fixedlymounted around the shaft 2, wire coils 5 wound along slots 4 formed atthe core 3, and a commutator 6 mounted to the shaft 2 near one end ofthe shaft 2. When the armature 1, which is the rotor of a motor, isunbalanced about its rotating axis in terms of weight, it may vibrateduring its rotation.

For this reason, the balance accuracy of the armature 1 has a closerelation with the performance of the motor using the armature 1 as itsrotor. Since recent industrial developments cause an increased demandfor motors having a superior performance, more accurate armatures havinga higher balance accuracy have been required.

Now, the configuration of the conventional 6-axis armature balancingmachine for measuring the balance of the above described armature, andmachining the armature based on the measured result, will be describedwith reference to FIG. 2 a. As shown in FIG. 2 a, the 6-axis armaturebalancing machine includes a lift unit L for supplying the armature 1 tobe subjected to a measuring process, and discharging the measuredarmature 1 to be subjected to a machining process, and a first balancemeasuring unit B1 for measuring unbalance amounts and positions of thearmature 1 at opposite axial portions, that is, left and right axialportions, of the core 3 in the armature 1, respectively. The armaturebalancing machine also includes a first cutting unit C1 for removing theunbalance amount of the armature 1 measured by the first balancemeasuring unit B1 at the left portion of the core 3, in accordance witha cutting process using a cutting tool, a rotating unit R for rotatingthe armature 1 to position the right unbalanced portion of the armature1 at a cutting point, and a second balance measuring unit B2 forre-measuring a possible unbalance amount of the armature 1 subjected tothe cutting process at its left and right unbalanced portions. Thearmature balancing machine further includes an index device I forfeeding the armature 1 to each of the units L, B1, C1, R, C2, and B2while being vertically movable, and a control unit (not shown) fordetecting the unbalance amounts and positions of the armature 1 based onsignals outputted from the balance measuring units B1 and B2, andoutputting operation control signals, generated based on the detectedresults, to the remaining units L, C1, R, and C2, thereby compensatingfor the unbalance of the armature 1. The index device I includes: aplurality of index arms having the same number as that of the abovedescribed units, and a finger unit 20.

Each of the balance measuring units B1 and B2 includes a servo motor orstepping motor having a pulley to which the armature 1 is connected viaa belt, and a balance measuring section arranged near the armature 1 tomeasure the unbalance amount and position of the armature 1. The controlunit rotates the armature 1 at a predetermined RPM by outputting pulsesto the drive motor, based on a vibration signal generated through avibration measuring sensor alone or together with a reference pointsensor. During the rotation of the armature 1, the control unit detectsthe position (angle) and unbalance amount of each unbalanced portion inthe armature 1 through a calculation circuit and a calculation program.The calculation circuit and program may be of various types, forexample, an AIFA WATT METRIC type, a FILT type, an FFT type, a WATTMETRIC type, or a synchronous rectification type.

The control unit also generates operation control signals based onsignals outputted from the balance measuring units B1 and B2, andoutputs those operation control signals to the lift unit L, cuttingunits C1 and C2, and rotating unit R, respectively. Under the control ofthe control unit, respective unbalanced portions of the armature 1 arepositioned at cutting points of cutting tools included in the cuttingunits C1 and C2 by the index device I. When the armature 1 is fed to thefirst cutting unit C1 or the second cutting unit C2 by the index deviceI, its unbalanced portion is cut by the associated cutting unit inaccordance with a cut depth and axial cutting length determined by apredetermined unbalance amount.

The configuration of the conventional 2-axis armature balancing machinewill be described with reference to FIG. 2 b. As shown in FIG. 2 b, the2-axis armature balancing machine includes a balance measuring unit B3for measuring respective unbalance amounts and positions of the armature1 at opposite axial portions, that is, left and right axial portions, ofthe core 2 in the armature 1 fed by a conveyor belt, a cutting unit C3for cutting the armature 1, based on each unbalance amount measured bythe balance measuring unit B3, and a rotating unit R3 for rotating thearmature 1, based on each unbalance position measured by the balancemeasuring unit B3. The 2-axis armature balancing machine also includesan index device I3 for feeding the armature 1 completing its unbalancetest from the balance measuring unit B3 to the cutting unit C3, upwardlymoving, rotating 180°, and then downwardly moving the cutting unit C3 onthe cutting unit C3 for cutting the left and right portions of thearmature 1, and feeding again the corrected armature 1 from the cuttingunit C3 to the balance measuring unit B3. The 2-axis armature balancingmachine further includes a control unit for outputting operation controlsignals to the rotating unit R3, cutting unit C3, and index device I3 inorder to achieve an unbalance correction based on the signal outputtedfrom the balance measuring unit B3. In the 2-axis armature balancingmachine, the armature 1, which has vertically moved by the index deviceI3, may be 180° rotated without being downwardly moved. That is, thearmature 1 can be rotated at a fixed position by the rotating unit R3.

The cutting amount in the cutting process is determined by the upwardmovement length of a blade included in the cutting tool, and the axialforward and backward movement length of the blade. The upward movementlength of the blade, that is, the cutting depth, and the axial forwardand backward movement length, that is, the axial cutting length, are setbased on the unbalance amount of the armature by the user. Examples ofthis setting are illustrated in FIG. 3.

FIG. 3 shows graphs depicting an unbalance correction amount varyingdepending on the unbalance amount. As indicated by the graph denoted bythe reference numeral “1”, the cutting depth and axial cutting lengthare set based on each of sampled unbalance amounts. For example, theunbalance correction amount may be 0.1 mm for an unbalance amount of 50mg, and 0.2 mm for an unbalance amount of 100 mg. When a measuredunbalance amount is determined to be within a range between the setunbalance amounts, the associated cutting depth and axial cutting lengthare determined by proportionally estimating them based on the setvalues.

FIGS. 2 a to 3 illustrate an example in which a subtractive unbalancecorrection is carried out. In the case of an additive unbalancecorrection, the balancing machine automatically discharges a weightdetermined based on the predetermined unbalance amount, and attaches thedischarged weight to the rotor at its unbalance position. In order todischarge a desired weight amount, discharge time and pressure areadjusted.

Although the unbalance correction by the balancing machine has beendescribed as being applied to armatures, it may be applicable to anyobjects requiring balance correction. Since these objects may beappreciated by those skilled in the art, no detailed description thereofwill be given.

However, the above described balancing machine may involve errors inunbalance correction position and amount due to an erroneous setting ofthe cutting tool, a linear or non-linear abrasion of the blade edge inthe cutting tool occurring during its use due to an erroneous setting ofthe cutting tool, an angular error generated during the rotation of theindex device, vertical and axial mechanical tolerances occurring duringthe vertical and axial movements of the index device, a mechanicaltolerance caused by a temperature difference, an erroneous measurementof unbalance angle and amount occurring due to a variation inmeasurement condition caused by an abrasion of the belt or drive pulley,or erroneous unbalance correction position and amount caused by variouserrors generated due to a variation in the temperature characteristicsof various electronic elements included in the control unit. Examples ofsuch errors will now be described with reference to FIGS. 3 to 5 d.

Although an unbalance amount and an unbalance correction amountaccording to the unbalance amount should be linearly proportional toeach other, as indicated by the graph 1 of FIG. 3, their practicalrelation is non-linear, as indicated by graphs 2 and 3 in FIG. 3. Such anon-linearity results from the above described causes of variousunbalance correction errors.

As described above, unbalance correction errors may be generated due toan erroneous setting of the cutting tool. For example, the cutting toolshould be set in such a fashion that the blade edge 9 and the armature 1are concentric, as shown in a part “a” of FIG. 4. However, where theblade edge 9 and the armature 1 are eccentric, as shown in a part “b” or“c” of FIG. 4, that is, an erroneous setting of the cutting tool occurs,the unbalance correction is not achieved at a correct position, asindicated by black portions in the parts “a” to “c” of FIG. 4.

Where there is no error in association with the unbalance correctionposition, as shown in the part “a” of FIG. 4, the corrected position isat 0° or 180° under the condition in which the initial unbalanceposition is 0° (FIG. 5 a), as shown in FIG. 5 b. In the case of thearmature having an unbalance at a position indicated by a black circlein the part “A-1” of FIG. 5 b, its unbalance correction is accuratelymade at a position of 0°. When the unbalance correction amount is lessthan the unbalance amount in the case shown in the part “A-1” of FIG. 5b, there is an unbalance amount remaining at the position of 0° afterthe unbalance correction, as shown in the part “A-2” of FIG. 5 b. On theother hand, when the unbalance correction amount is more than theunbalance amount, there is an unbalance amount remaining at a positionopposite to the initial unbalance position after the unbalancecorrection, as shown in the part “A-3” of FIG. 5 b. In this case, theinitial unbalance position is shifted by an angle of 180°. In eithercase, the unbalance correction amount should be adjusted becausealthough the unbalance correction position is correct, there is an errorin the unbalance correction amount.

Where there is an error in unbalance position (angle) due to variousfactors including the erroneous setting as shown in the part “b” or “c”of FIG. 4, the unbalance correction is carried out at an incorrectposition, as shown in FIG. 5 c or 5 d. This will be described in detailhereinafter.

Results shown in FIG. 5 c are generated when there is an error inunbalance correction position, and the correction amount is less thanthe unbalance amount. Although the initial unbalance position is theposition of 0°, as shown in FIG. 5 a, an angular error may occur due toa composite reason, as shown in the part “B-1” or “C-1” of FIG. 5 c. Inthis case, the unbalance correction is carried out in accordance with acorrection angle and correction amount vector-calculated based on themeasured unbalance amount and the erroneous angle as shown in the part“B-1” or “C-1” of FIG. 5 c. In the cases respectively shown in the parts“B-1” to “B-3” and “C-1” to “C-3” of FIG. 5 c, their angular errors(angular deviations) have relations of “B-1<B-2<B-3” and “C-1<C-2<C-3”with respect to 0°. That is, the case “B-2” has an angular deviationtoward 270° larger than that of the case “B-1”, and the case “B-3” hasan angular deviation toward 270° larger than that of the case “B-2”. Onthe other hand, the case “C-2” has an angular deviation toward 90°larger than that of the case “C-1”, and the case “IC-3” has an angulardeviation toward 90° larger than that of the case “C-2”.

Results shown in FIG. 5 d are generated when there is an error inunbalance correction position, and the correction amount is more thanthe unbalance amount. Although the initial unbalance position is theposition of 0°, as shown in FIG. 5 a, an angular error may occur due toa composite reason, as shown in the part “D-1” or “E-1” of FIG. 5 d. Inthis case, the unbalance correction is carried out in accordance with acorrection angle and correction amount vector-calculated based on themeasured unbalance amount and the erroneous angle as shown in the part“D-1” or “E-1” of FIG. 5 d. In the cases respectively shown in the parts“D-1” to “D-3” and “E-1” to “E-3” of FIG. 5 d, their angular errors(angular deviations) have relations of “D-1<D-2<D-3” and “E-1<E-2<E-3”with respect to 0°. That is, the case “ID-2” has an angular deviationtoward 270° larger than that of the case “D-1”, and the case “D-3” hasan angular deviation toward 270° larger than that of the case “D-2”. Onthe other hand, the case “D-2” has an angular deviation toward 90°larger than that of the case “D-1”, and the case “D-3” has an angulardeviation toward 90° larger than that of the case “D-2”.

When the unbalance compensation is inaccurately achieved, as mentionedabove, there is a problem in that the probability that the rotoremerging from the balancing machine has a good quality is reduced to 60%or less. Once the primary unbalance correction is made at a certainposition, it is impossible to carry out a re-correction at the sameposition. For this reason, there is a large defective proportion ofproducts. In the case of an additive unbalance correction, there is aproblem in that the weight attached to the rotor may be separated fromthe rotor during the operation of the rotor. Furthermore, there is wasteof resources because most of rotors determined to have a poor qualitymust be disposed of.

In order to reduce the defective proportion of products, a new settingof the balancing machine may be carried out under the condition in whichthe balancing machine is stopped, in accordance with conventionaltechniques. Conventionally, the setting of the balancing machine iscarried out periodically or whenever it is determined that the rate ofproducts having a poor quality is too high. The adjustment of thecutting depth and axial movement distance of the cutter associated withthe setting of the balancing machine is determined only based on theimmediate perception of the operator. For this reason, there is alimitation in reducing the rate of products having a poor quality.Moreover, the quality of products is limited. Also, there is adegradation in productivity.

DISCLOSURE OF THE INVENTION

Therefore the present invention has been made in view of the abovementioned problems, and an object of the invention is to provide amethod for automatically compensating for an unbalance correctionposition and correction amount in a balancing machine, which is capableof greatly reducing the rate of products, for example, rotors, having apoor quality due to an erroneous unbalance correction, while achieving agreat improvement in productivity.

In accordance with the present invention, this object is accomplished byproviding a method for automatically compensating for an unbalancecorrection position and an unbalance correction amount in a balancingmachine, comprising: an unbalance testing procedure for measuring anunbalance amount and an unbalance position of a rotor completing aprimary unbalance correction thereof; an initial unbalance amountdetermining procedure for determining whether or not an initialunbalance amount present before the unbalance correction is not morethan a predetermined value corresponding to an unbalance amountcorrectable by a one-time correction; a counting procedure forincrementing a counted value when it is determined in the initialunbalance amount determining procedure that the initial unbalance amountis not more than the predetermined value; a good-quality determiningprocedure for determining whether or not the unbalance amount measuredin the unbalance testing procedure is more than a reference value fordetermining whether or not the rotor has a good quality; an angulardeviation measuring procedure for measuring an angular deviation betweenan unbalance position before the unbalance correction and the unbalanceposition after the unbalance correction when it is determined in thegood-quality determining procedure that the measured unbalance amount ismore than the good-quality reference value; an angular deviation rangedetermining procedure for determining whether the angular deviation ofthe unbalances position measured in the angular deviation measuringprocedure is within a range of 0°±X1° (0<X1<5), a range of 180°±X1°, arange of 0°+X2° (X1<X2<90), a range of 180°+X2°, a range 0°−X2°, or arange of 180°−X2°; and an unbalance correction position and amountcompensating procedure for, when the counted value reaches apredetermined value for calculation of an average value, comparing thenumber of times when the angular deviation of the unbalance position iswithin the range of 0°+X2° or 180°+X2° with the number of times when theangular deviation of the unbalance position is within the range of0°−X2° or 180°−X2°, angularly compensating for the unbalance correctionsposition based on the angular deviation of the unbalance positionassociated with a higher-number one of the compared ranges, comparingthe number of times when the angular deviation of the unbalance positionis within the range of 0°±X1° in accordance with an insufficientunbalance correction at an accurate correction position with the numberof times when the angular deviation of the unbalance position is withinthe range of 180°±X1° in accordance with an excessive unbalancecorrection at an accurate correction position, and compensating for theunbalance correction amount in accordance with a higher-number one ofthe ranges of 0°±X1° and 180°±X1° to increase the unbalance correctionamount when the higher-number range is 0°±X1° while reducing theunbalance correction amount when the higher-number range is 180°±X1°.

Preferably, it is determined in the good-quality determining procedurewhether or not the rotor has a good quality, based on a value obtainedby deducting, from the good-quality reference value, a value optionallyset for an improvement in the accuracy of a cutting depth for theunbalance correction.

The automatic compensation method may further comprise a correctionamount re-setting procedure for dividing a unbalance amount rangemeasurable prior to the unbalance correction into a plurality ofsub-ranges, executing the unbalance testing procedure through theangular deviation range determining procedure for each of the unbalanceamount sub-ranges to compare the number of times when the angulardeviation of the unbalance position is within the range of 0°±X1° withthe number of times when the angular deviation of the unbalance positionis within the range of 180°±X1°, and re-setting an unbalance correctionamount for the unbalance amount sub-range in accordance with ahigher-number one of the ranges of 0°±X1° and 180°±X1°.

The automatic compensation method may further comprise a procedure fordisplaying a current condition of the balancing machine including afinally determined unbalance position error range, a rate of productshaving a good quality, and a correction amount error, and a procedurefor automatically stopping an operation of the balancing machine inaccordance with a self determination of the balancing machine when acurrent machine condition value reaches a predetermined value at whichit is impossible for the balancing machine to operate, and warning anoperator of the current machine condition.

The compensation for the unbalance correction position in the unbalancecorrection position and amount compensating procedure may be carried outby correcting only the unbalance correction amount.

The compensation for the unbalance correction position in the unbalancecorrection position and amount compensating procedure may carried out bycorrecting both the unbalance correction position and the unbalancecorrection amount based on a value obtained by vector-calculating themeasured unbalance position and unbalance amount.

Alternatively, the compensation for the unbalance correction position inthe unbalance correction position and amount compensating procedure maybe carried out by repeatedly performing the unbalance correction undercondition in which the unbalance correction position is optionallyshifted with reference to 0° or 180°, storing a correction rate at everyunbalance correction, calculating a maximum one of stored correctionrates, and correcting the unbalance correction position based on thecalculated maximum correction rate.

The automatic compensation method may further comprise a basic datastoring procedure for storing, as basic data, cutting data exhibiting apredetermined high correction rate or more so that the basic data isused as recovery data when a degradation in correction rate occurs, andan automatic basic data recovering procedure for automaticallyrecovering the stored basic data as cutting data when the correctionrate is reduced to a predetermined value.

BRIEF DESCRIPTION OF THE DRAWINGS

The above object, and other features and advantages of the presentinvention will become more apparent after a reading of the followingdetailed description when taken in conjunction with the drawings, inwhich:

FIGS. 1 a and 1 b are perspective views respectively illustratinggeneral armatures;

FIG. 2 a is a plan view illustrating a conventional 6-axis armaturebalancing machine;

FIG. 2 b is a plan view illustrating a conventional 2-axis armaturebalancing machine;

FIG. 3 is a graph depicting an unbalance correction amount varyingdepending on an unbalance amount in a conventional balancing machine;

FIG. 4 is a view illustrating examples of an erroneous unbalancecorrection caused by setting errors in a cutting tool in conventionalcases;

FIG. 5 a is a view illustrating a master unbalance position and amount;

FIGS. 5 b to 5 d are views respectively illustrating examples of anerroneous unbalance correction in conventional cases;

FIGS. 6 a and 6 b are graphs each depicting the relation between anunbalance amount and a correction amount in a balancing machineaccording to the present invention;

FIG. 7 is a diagram for calculating angular deviations;

FIGS. 8 a to 8 c are flow charts illustrating a method for automaticallycompensating for an unbalance correction position and correction amountin the balancing machine according to the present invention;

FIG. 9 is a flow chart illustrating an angular condition displayprocedure according to the present invention; and

FIG. 10 is a flow chart illustrating a machine condition displayprocedure according to the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Now, preferred embodiments of the present invention will be described indetail with reference to the annexed drawings.

FIGS. 6 a and 6 b are graphs each depicting the relation between anunbalance amount and a correction amount (depth and length) in abalancing machine according to the present invention. FIG. 7 is adiagram for calculating angular deviations. FIGS. 8 a to 8 c are flowcharts illustrating a method for automatically compensating for anunbalance correction position and correction amount in the balancingmachine according to the present invention. FIG. 9 is a flow chartillustrating an angular condition display procedure according to thepresent invention. FIG. 10 is a flow chart illustrating a machinecondition display procedure according to the present invention.

The method for automatically compensating for the unbalance correctionposition and unbalance correction amount in the balancing machineaccording to the present invention involves:

an unbalance testing procedure for measuring the unbalance amount and:,unbalance position of a rotor completing its primary unbalancecorrection;

an initial unbalance amount determining procedure for determiningwhether or not the unbalance amount present before the unbalancecorrection is not more than a predetermined value corresponding to anunbalance amount determined by the operator to be correctable by aone-time correction;

a counting procedure for incrementing a counted value when it isdetermined in the initial unbalance amount determining procedure thatthe initial unbalance amount is not more than the predetermined value;

a good-quality determining procedure for determining whether or not theunbalance amount measured in the unbalance testing procedure is morethan a reference value for determining whether or not the rotor has agood quality (hereinafter, the reference value is referred to as a“good-quality reference value”);

an angular deviation measuring, procedure for measuring an angulardeviation between the unbalance position before the unbalance correctionand the unbalance position after the unbalance correction when it isdetermined in the good-quality determining procedure that the measuredunbalance amount is more than the good-quality reference value;

an angular deviation range determining procedure for determining whetherthe angular deviation of the unbalance position measured in the angulardeviation measuring procedure is within a range of 0°±X1° (0<X1<5), arange of 180°±X1°, a range of 0°+X2° (X2 is a maximum correctableangular unbalance error value, and X1<X2<90), a range of 180°+X2°, arange 0°−X2°, or a range of 180°−X2°; and

an unbalance correction position and amount compensating procedure for,when the counted value reaches a predetermined value for calculation ofan average value, comparing the number of times when the angulardeviation of the unbalance position is within the range of 0°+X2° or180°+X2° with the number of times when the angular deviation of theunbalance position is within the range of 0°−X2° or 180°−X2°, angularlycompensating, for the unbalance correction position based on the angulardeviation of the unbalance position associated with a higher-number oneof the compared ranges, comparing the number of times when the angulardeviation of the unbalance position is within the range of 0°±X1° inaccordance with an insufficient unbalance correction at an accuratecorrection position with the number of times when the angular deviationof the unbalance position is within the range of a range of 180°±X1° inaccordance with an excessive unbalance correction at an accuratecorrection position, and compensating for the unbalance correctionamount in accordance with a higher-number one of the ranges of 0°±X1°and 180°±X1° to increase the unbalance correction amount when thehigher-number range is 0°±X1° while reducing the unbalance correctionamount when the higher-number range is 180°±X1°.

In the unbalance correction position and amount compensating procedure,the compensation for the correction position is carried by correctingonly the unbalance correction amount correcting both the unbalancecorrection position and amount based on the vector-calculated unbalancecorrection position and amount, or repeatedly performing the correctionunder condition in which the correction position is optionally shiftedwith reference to 0° or 180°, storing the correction rates, calculatingthe maximum one of the correction rates, and correcting the unbalancecorrection position based on the calculated maximum correction rate.

In the method for automatically compensating for the unbalancecorrection position and correction amount in the balancing machineaccording to the present invention, the compensation for the unbalanceamount may be carried out in a subtractive fashion or in an additivefashion. In accordance with the subtractive compensation, the unbalanceamount is corrected by partially cutting a heavier portion of the rotor.In accordance with the additive compensation, the unbalance amount iscorrected by adding a weight to a lighter portion of the rotor.Therefore, the correction of the unbalance amount should be carried outin an appropriate manner determined in accordance with the usedcompensation method. This will be described in detail hereinafter. Whenthe result of a re-measurement conducted following the unbalancecorrection corresponds to 0°±X1° under the condition in which theunbalance correction position is 0°, that is, the heavier portion of therotor is positioned at 0° in the case of the subtractive unbalancecorrection, it is necessary to increase the cutting depth or axialmovement distance of the cutter because the rotor is insufficiently cut.Primarily, the cutting depth is appropriately increased. When thecompensation for the unbalance amount by the increase in cutting depthis insufficient, the axial movement distance of the cutter is thenincreased. When the result of the re-measurement corresponds to180°±X1°, it is necessary to reduce the cutting depth or axial movementdistance of the cutter because the rotor is excessively cut. On theother hand, when the result of the re-measurement corresponds to 0°±X1°in the case of the additive unbalance correction, it is necessary toreduce the weight compensation amount because the weight compensation isexcessive. When the result of the re-measurement in the case of theadditive unbalance correction corresponds to 180°±X1°, it is necessaryto increase the weight compensation amount because the weightcompensation is insufficient.

In the good-quality determining procedure, it is determined whether ornot the rotor has a good quality, based on a value obtained bydeducting, from the good-quality reference value, a value optionally setby the operator for an improvement in the accuracy of the cutting depth.

In accordance with the method for automatically compensating for theunbalance correction position and correction amount in the balancingmachine according to the present invention, the unbalance amountmeasurable prior to the unbalance correction is divided into a pluralityof ranges. That is, the possible unbalance amount range is divided intoa plurality of sub-ranges D0 to Dn or L0 to Ln, as shown in FIG. 6 a or6 b. Each unbalance amount range may be subdivided again. For each ofthe unbalance amount sub-ranges, the unbalance testing procedure throughthe angular deviation range determining procedure are carried out. Inaccordance with the present invention, the automatic compensation methodfurther involves a correction amount re-setting procedure for comparingthe angular deviation of 0°±X1° and the angular deviation of 180°±X1°,and re-setting a desired unbalance correction amount (depth and length)based on the unbalance amount associated with the angular deviationdetermined to occur more frequently. The unbalance amount and theunbalance correction amount for the unbalance amount, which areinitially set in the balancing machine, are proportional to each otherin such a fashion that the correction depth or length is linearlyproportional to the unbalance amount, as indicated by the line 1 in FIG.6 a or 6 b. However, the unbalance amount and the unbalance correctionamount have a non-linear relation in practical cases-due to variousfactors such as various machine conditions, as indicated by the line 2in FIG. 6 a or 6 b. In accordance with the present invention, therefore,the unbalance correction amount is accurately and automatically re-setin the above described re-setting procedure, based on the generatederror, so that the relation between the unbalance amount and theunbalance correction amount is corrected from that of the line 1 in FIG.6 a or 6 b to that of the line 2 in FIG. 6 a or 6 b. Accordingly, thedefective proportion of products is greatly reduced. Heretobefore, thesubtractive unbalance correction has been described in conjunction withFIGS. 6 a and 6 b. The additive unbalance correction may be carried outin the same manner as that of the subtractive unbalance correction,except that the discharge time and pressure of a weight is controlled.Accordingly, no description and illustration will be given inconjunction with the additive unbalance correction.

The method for automatically compensating for the unbalance correctionposition and correction amount in the balancing machine according to thepresent invention further involves a procedure for displaying thecurrent condition of the balancing machine including the finallydetermined unbalance position error range (that is, angular conditionrate), the rate of products having a good quality, and the correctionamount error, and a procedure for automatically stopping the operationof the balancing machine in accordance with a self determination of thebalancing machine when the current machine condition value reaches apredetermined value at which it is impossible for the balancing machineto operate, and warning the operator of the current machine condition.Based on the displayed current machine condition, the operatoroptionally stops the balancing machine to check it. Even when no machinechecking is carried out by the operator, the balancing machineautomatically determines whether or not the current machine condition ispoor, that is, capable of producing defective products. When it isdetermined that the current machine condition is poor, that is, capableof producing defective products, the balancing machine informs theoperator of the problematic machine condition by displaying a warningsign or generating a buzz, or stops by itself, thereby avoiding anerroneous unbalance correction caused by an erroneous operation of thebalancing machine. If there is no function of displaying the currentmachine condition or of appropriately stopping the balancing machine, itis impossible to determine whether or not the balancing machine operateserroneously even when the operator continuously monitors the currentmachine condition. The operator can check the erroneous operation of thebalancing machine, only after monitoring generation of defectiveproducts. When the erroneous operation of the balancing machine iscontinuously carried out, the rate of products having a good qualityafter the balance correction is considerably lowered. Consequently, therate of products having a good quality may reach 0%.

The cutting data may have errors when the automatic compensation for thecutting depth is erroneously made due to defects present at productsthemselves, setting errors occurring in measuring parts, setting errorsgenerated by the operator. In this case, therefore, it is desirable torecover the erroneously compensated cutting data to the original data.To this end, the method for automatically compensating for the unbalancecorrection position and unbalance correction amount in the balancingmachine according to the present invention further involves a basic datastoring procedure for storing, as basic data, cutting data exhibiting ahigh correction rate of, for example, 97% or more so that the basic datais used as recovery data when a degradation in correction rate occurs.The correction rate may be calculated for a desired number of products,for example, 50 products. Also, the method for automaticallycompensating for the unbalance correction position and unbalancecorrection amount in the balancing machine according to the presentinvention further involves an automatic basic data recovering procedurefor automatically recovering the stored basic data as cutting data whenthe correction rate is reduced to a predetermined value, for example,90% or less. When the automatic basic data recovering procedure isrepeated a predetermined number of times or more, for example, two timesor more, an error message is displayed, and the balancing machine isstopped.

Meanwhile, the reason why the range of ±X1° is involved with themeasurement of the angular deviation is that the unbalance point cannotbe positioned at 0° or 180° due to errors present in the balancingmachine itself.

The angular condition rate ACR can be derived using the followingExpression 1. The angular error in Expression 1 can be calculated asfollows: where the unbalance position measured to have an unbalanceangle D after the one-time unbalance correction is positioned at a point{circle around (1)} (0<D<X2), as shown in FIG. 7, the angular error αcorresponds to the measured angle, that is, D°; where the unbalanceposition measured after the one-time unbalance correction is positionedat a point {circle around (2)} (D<360−X2), the angular error acorresponds to a value obtained by deducting 360° from the measuredangle of D°; where the unbalance position measured after the one-timeunbalance correction is positioned at a point {circle around (3)}(180−X2<D<180), the angular error a corresponds to a value obtained bydeducting 180° from the measured angle of D°; and where the unbalance:position measured after the one-time unbalance correction is positionedat a point {circle around (4)} (180<D<180+X2), the angular error αcorresponds to a value obtained by deducting 180° from the measuredangle of D°

$\begin{matrix}{{ACR} = \frac{100 \times \frac{\begin{matrix}{{\text{Average~~Value~~of~~Angular~~Error}} +} \\{\text{Standard~~Deviation~~of~~Angular~~Error}}\end{matrix}}{2}}{X2}} & \left\lbrack {{Expression}\mspace{14mu} 1} \right\rbrack\end{matrix}$

Now, the preferred embodiment of the present invention having the abovedescribed features will be described in detail with reference to FIGS. 8a to 10. The illustrated embodiment of the present invention isassociated with the case in which unbalance correction is carried out ina subtractive fashion for respective left and right axial portions of ageneral rotor. Accordingly, the correction of an unbalance correctionamount corresponds to the correction of a cutting depth. Thecompensation for the unbalance correction amount may be achieved bycorrecting only the cutting depth or the cutting length, or correctingboth the cutting depth and the cutting length, as will be appreciated bythose skilled in the technical field. Accordingly, only the methodassociated with the correction of the cutting depth will be described.

The additive unbalance correction may be carried out in the same manneras that of the subtractive unbalance correction, except that the weight(discharge time and pressure) is controlled in place of the cuttingdepth or length. Accordingly, no description or illustration will begiven in conjunction with the additive unbalance correction.

FIGS. 8 a to 8 c are flow charts illustrating sequential steps of themethod for automatically compensating for the unbalance correctionposition and correction amount in the balancing machine according to thepresent invention. FIG. 9 is a flow chart illustrating the angularcondition displaying procedure according to the present invention. FIG.10 is a flow chart illustrating the machine condition displayingprocedure according to the present invention. The method of the presentinvention will be described in more detail with reference to FIGS. 8 ato 10 in conjunction with the case wherein an armature is corrected forits unbalance in a subtractive fashion under the condition in which itsunbalance correction position is 0°.

In accordance with the method of the present invention, the initialunbalance position and unbalance amount of an armature are primarilymeasured (Step S100). After completing an unbalance correction at boththe left and right portions L and R of the armature (Step S101), theunbalance position and unbalance amount of the armature are measuredagain (Step 102). It is then determined whether or not the unbalanceamount present at each of the left and right armature portions L and Rbefore the unbalance correction, that is, the initial unbalance amount,is more than a predetermined value X3 corresponding to an unbalanceamount determined to be correctable by a one-time correction (StepS103).

The predetermined value X3 used in step S103 is optionally set by theoperator. Where the initial unbalance amount at each of the left andright armature portions L and R is more than the predetermined value X3,the procedure is returned to step S100 for a secondary unbalancecorrection because the unbalance at the left or right armature portion Lor R cannot be corrected by a one-time correction.

On the other hand, where the initial unbalance amount at each of theleft and right armature portions L and R is not more than thepredetermined value X3, an incrementation in counted value by one iscarried out (Step S104). An angular deviation between the unbalanceposition measured at step S102 and the unbalance position measuredbefore the unbalance correction is calculated (Step S105). Based on thecalculated angular deviation, errors in the unbalance position and depthare determined. This determination will be described in detailhereinafter.

First, it is determined whether or not the unbalance amount measured atthe left armature portion L is more than a reference value X4 (StepS106). The reference value X4 is obtained by deducting a predeterminedvalue from a value corresponding to a good quality. When the leftunbalance amount is more than the reference value X4, it is determinedwhether or not the angular deviation between the unbalance positionmeasured before the unbalance correction and the unbalance positionmeasured after the unbalance correction corresponds to 0°±X1° (0<X1<5)(Step S107). When the angular deviation corresponds to 0°±X1°, that is,when the unbalance position measured after the one-time unbalancecorrection corresponds to 0°±X1° in the case in which the initialunbalance position is set to be 0°, the counted value of a plus counterfor correction of the left unbalance correction amount is incremented(Step S108). On the other hand, when the angular deviation does notcorrespond to 0°±X1°, it is then determined whether or not the angulardeviation corresponds to 180°±X1° (Step S109). Where the angulardeviation corresponds to 180°±X1°, the counted value of a minus counterfor correction of the left unbalance correction amount is incremented(Step S110). On the other hand, where the angular deviation does notcorrespond to 180°±X1°, it is then determined whether the angulardeviation corresponds to 0°−X2° or 180°−X2° (X1<X2<90) (Step S111). Whenit is determined that the angular deviation corresponds to 0°−X2° or180°−X2°, the counted value of a plus counter for correction of the leftangle deviation is incremented (Step S112). On the other hand, when itis determined that the angular deviation does not correspond to 0°−X2°or 180°−X2°, it is then determined whether the angular deviationcorresponds to 0°+X2° or 180°+X2° (Step S113). When the angulardeviation corresponds to 0°+X2° or 180°+X2°, the counted value of aminus counter for correction of the left angle deviation is incremented(Step S114).

Meanwhile, where the angular deviation does not correspond to 0°+X2° or180°+X2°, it is then determined whether or not the unbalance amountmeasured at the right armature portion R is more than the referencevalue X4 (Step S115). When the right unbalance amount is more than thereference value X4, it is determined whether or not the angulardeviation between the unbalance position measured before the unbalancecorrection and the unbalance position measured after the unbalancecorrection corresponds to 0°±X1° (Step S116). When the angular deviationcorresponds to 0°±X1°, the counted value of a plus counter forcorrection of the right unbalance correction amount is incremented (StepS117). On the other hand, when the angular deviation does not correspondto 0°±X1°, it is then determined whether or not the angular deviationcorresponds to 180°±X1° (Step S118). Where the angular deviationcorresponds to 180°±X1°, the counted value of a minus counter forcorrection of the right unbalance correction amount is incremented (StepS119). On the other hand, where the angular deviation does notcorrespond to 180°±X1°, it is then determined whether the angulardeviation corresponds to 0°−X2° or 180°−X2° (Step S120). When it isdetermined that the angular deviation corresponds to 0°−X2° or 180°−X2°,the counted value of a plus counter for correction of the right angledeviation is incremented (Step S121). On the other hand, when it isdetermined that the angular deviation does not correspond to 0°−X2° or180°−X2°, it is then determined whether the angular deviationcorresponds to 0°+X2° or 180°+X2° (Step S122). When the angulardeviation corresponds to 0°+X2° or 180°+X2°, the counted value of aminus counter for correction of the right angle deviation, isincremented (Step S123).

Where it is determined at step S106 that the left unbalance amount isnot more than the reference value X4, and it is then determined at step115 that the left unbalance amount is not more than the reference valueX4, in accordance with a normal unbalance correction, or where theprocedure for determining errors in the unbalance position and depth atboth the left and right armature portions is completed, it is determinedwhether or not the counted value incremented at step S104 reaches apredetermined value X5 optionally set by the operator to obtain anaverage value (Step S124). When the counted value is less than thepredetermined value X5, the procedure is returned to step S100. On theother hand, when the counted value is not less than the predeterminedvalue X5, a procedure for correcting each of the left and rightunbalance correction amounts is carried out. This procedure will now bedescribed.

It is first determined whether or not the counted value of the pluscounter for correction of the left unbalance correction amount is morethan the counted value of the minus counter for correction of the leftunbalance correction amount (Step S125). When it is determined that thecounted value of the plus counter is more than the counted value of theminus counter, the left unbalance correction amount is increased by apredetermined value (Step S126). This value is optionally set by theoperator in accordance with a processing condition, but it is set to be0.001 mm in accordance with the present invention. On the other hand,when the counted value of the minus counter is not more than the countedvalue of the plus counter (Step S127), the left unbalance correctionamount is reduced by the predetermined value (Step S128).

It is then determined whether or not the counted value of the pluscounter for correction of the left angle deviation is more than thecounted value of the minus counter for correction of the left angledeviation (Step S129). When it is determined that the counted value ofthe plus counter is more than the counted value of the minus counter,the cutting position is shifted in a left direction by a compensationangle obtained by vector-calculating the unbalance amount and theunbalance angle (Step S130). On the other hand, when the counted valueof the minus counter is more than the counted value of the plus counter(Step S131), the cutting position is shifted in a right direction by thecompensation angle obtained by vector-calculating the unbalance amountand the unbalance angle (Step 5132).

After completion of the compensation for the left unbalance, acompensation for the right unbalance is carried out. First, it isdetermined whether or not the counted value of the plus counter forcorrection of the right unbalance correction amount is more than thecounted value of the minus counter for correction of the right unbalancecorrection amount (Step S133). When it is determined that the countedvalue of the plus counter is more than the counted value of the minuscounter, the right unbalance correction amount is increased by apredetermined value (Step S134). On the other hand, when the countedvalue of the minus counter is more than the counted value of the pluscounter (Step S135), the right unbalance correction amount is reduced bythe predetermined value (Step S128).

It is then determined whether or not the counted value of the pluscounter for correction of the right angle deviation is more than thecounted value of the minus counter for correction of the right angledeviation (Step S137). When it is determined that the counted value ofthe plus counter is more than the counted value of the minus counter,the cutting position is shifted in a left direction by a compensationangle obtained by vector-calculating the unbalance amount and theunbalance angle (Step S138). On the other hand, when the counted valueof the minus counter is more than the counted value of the plus counter(Step S139), the cutting position is shifted in a right direction by thecompensation angle obtained by vector-calculating the unbalance amountand the unbalance angle (Step S140)

After completion of the compensation for both the right and left angledeviations and both the right and left unbalance amounts in accordancewith the above described procedure, the counted value at step S104 isreset to be “0” (Step S141). In this state, angular and machineconditions are displayed, respectively (Steps S142 and S143).Thereafter, the entire procedure is repeated. The angular conditiondisplaying procedure and machine condition displaying procedure will nowbe described in detail with reference to FIGS. 9 and 10.

In the angular condition displaying procedure, the counted value of acounter for angular conditions is incremented in response to theincrementation operation at step S104 in the procedure of FIGS. 8 a to 8c (Step S201). The primarily-corrected left and right angular deviationsmeasured at step S102 are stored (Step S202)

Following the storage of the angular deviations, it is determinedwhether or not the counted value is more than a predetermined value(Step S203). When the counted value is not more than the predeterminedvalue, the procedure is returned to step S201. On the other hand, whenthe counted value is more than the predetermined value, an angularcondition rate is calculated based on the stored angular deviation datain accordance with the Expression 1, and the calculated angularcondition rate is displayed (Step S204). Thereafter, the angularcondition counter is reset (Step S205).

Subsequently, it is determined whether or not the angular condition ratecalculated at step S204 is less than a first predetermined angularcondition rate X6% (for example, 50%) (Step S206). Where the calculatedangular condition rate is less than the first predetermined angularcondition rate, the machine is stopped (Step S207). At step S207, awarning message recommending the operator to re-set the machine isdisplayed. Thereafter, the procedure is completed. On the other hand, ifthe calculated angular condition rate is not less than the firstpredetermined angular condition rate, it is then determined whether ornot the calculated angular condition rate is less than a secondpredetermined angular condition rate X7% (for example, 70%) (Step.S208). Where the calculated angular condition rate is less than thesecond predetermined angular condition rate X7%, a warning message isdisplayed which informs the operator of the fact that the currentangular condition is bad (Step S209). The procedure is then completed.On the other hand, when the calculated angular condition rate is notless than the second predetermined angular condition rate X7%, theprocedure is completed.

In the machine condition displaying procedure, the counted value of acounter for machine conditions is incremented in response to theincrementation operation at step S104 in the procedure of FIGS. 8 a to 8c (Step S301). Respective initial correction success rates for the leftand right portions of the rotor measured at step S102 after the primaryunbalance correction are stored (Step S302).

Following the storage of the initial correction success rates, it isdetermined whether or not the counted value is more than a predeterminedvalue (Step S303). When the counted value is not more than thepredetermined value, the procedure is returned to step S301. On theother hand, when the counted value is more than the predetermined value,the left and right initial correction success rates are displayed, andthe counter for machine condition is reset. (Step S304).

Subsequently, it is determined whether or not the left or right initialcorrection success rate displayed at step S304 is less than a firstpredetermined correction success rate X8% (for example, 50%) (StepS305). When the left or right initial correction success rate is lessthan the first predetermined correction success rate X8%, the balancingmachine is stopped (Step S306). At step S306, a warning message is alsodisplayed to recommend the operator to re-set the balancing machine. Theprocedure is then completed. On the other hand, when the left and rightinitial correction success rates are not less than the firstpredetermined correction success rate X8%, it is determined whether ornot the left or right initial correction success rate, is less than asecond predetermined correction success rate X9% (for example, 70%)(Step S307). When the left or right initial correction success rate isless than the second predetermined correction success rate X9%, awarning message is displayed to inform the operator of the fact that thecurrent machine condition is bad (Step S308). The procedure is thencompleted. On the other hand, when the left and right initial correctionsuccess rates are not less than the second predetermined correctionsuccess rate X9%, the procedure is completed.

Meanwhile, the automatic compensation method for the unbalancecorrection position and amount described in conjunction with steps S101to S104 is carried out for the entire unbalance amount range withoutdividing the unbalance amount range into a plurality of sub-ranges priorto the unbalance correction, in order to compensate for the cuttingdepth and correction position errors caused by an abrasion of thecutter. Where the unbalance amount is re-set under the condition inwhich the unbalance amount range is divided into a plurality ofsub-ranges, this re-setting may be achieved in the same fashion as theprocedures of steps S101 to 141, except that the procedures aresub-divided, and the correction of the angular unbalance position isomitted. Accordingly, no further description will be given inconjunction with the above re-setting procedure.

Although the embodiment of the present invention has been described inconjunction with an armature to be corrected for unbalance at left andright axial portions thereof, the method of the present invention isapplicable to unbalance correction for various rotors, as will beappreciated by those skilled in the technical field. Accordingly, nofurther description will be given.

In accordance with the present invention, it is possible to greatlyreduce the defective proportion of products while achieving anenhancement in machining efficiency, and a great increase inproductivity because the unbalance correction position and amount of thecurrent rotor are automatically compensated for, based on the correctionamount of the previously-corrected rotor, thereby achieving an accurateunbalance correction.

INDUSTRIAL APPLICABILITY

As apparent from the above description, in accordance with the presentinvention, the unbalance correction position and amount of a rotor isautomatically compensated for, based on the unbalance correction amountof a previously-corrected rotor, so as to achieve an optimum unbalancecorrection in spite of the fact that there may be errors in unbalancecorrection position and amount due to an erroneous setting of thecutting tool, an abrasion of the blade edge in the cutting tooloccurring during its use due to an erroneous setting of the cuttingtool, a non-uniform abrasion of the cutting tool, vertical and axialmechanical tolerances occurring during the vertical and axial movementsof the index device, a mechanical tolerance caused by a temperaturedifference, an erroneous measurement of unbalance angle and amountoccurring due to a variation in measurement condition caused by anabrasion of the belt or drive pulley, or various angular errors anderroneous operations caused by a variation in time constant occurringdue to a variation in the temperature characteristics of variouselectronic elements. Accordingly, the rate of products having a goodquality obtained after a one-time correction in the balancing machinecan be 90% or more. Since the balancing machine can maintain a bestcondition by correcting its condition by itself in accordance with arandom variation in machine condition, it is possible to greatly reducethe amount of rotors to be disposed of. Accordingly, it is possible toachieve a considerable increase in productivity without any waste ofresources.

In conventional cases, there is a large defective proportion of productsbecause once the primary unbalance correction is made at a certainposition, it is impossible to carry out a re-correction at the sameposition. As a result, there is waste of resources. In the case of aconventional additive unbalance correction, there is an instability inuse in that the weight attached to the rotor may be separated from therotor during the operation of the rotor. However, there is no problem ofsuch as waste of resources in accordance with the present inventionbecause no erroneous unbalance correction occurs.

Since the unbalance correction amount can be re-set under the conditionin which it is divided into a plurality of sub-ranges in accordance withthe present invention, the balancing machine can be allowed tocompensate for randomly-generated mechanical or electrical variations.Accordingly, it is possible to achieve an unbalance correction with anincreased accuracy.

In accordance with the present invention, the balancing machine isequipped with functions of monitoring its machine condition, anddetermining, based on the monitored result, whether the balancingmachine operates continuously or displays its machine condition to allowthe operator to determine whether the balancing machine should becontinuously operated or stopped. Accordingly the operator can alwayscheck the condition of the balancing machine. Since the balancingmachine is automatically stopped when there are severe errors in theoperation of the balancing machine, it is possible to avoid an erroneousunbalance correction caused by errors occurring in the balancingmachine.

Conventionally, the operator optionally sets the unbalance correctionamount, that is, the cutting depth and axial cutting length inaccordance with only his judgment, taking into consideration theunbalance condition exhibited after the unbalance correction. For thisreason, where the cutter is replaced by a new one in conventional cases,a lot of time is taken for a setting procedure for obtaining an accurateunbalance correction. In accordance with the present invention, however,it is possible to achieve an accurate unbalance correction within ashort period of time after the replacement of the cutter because thebalancing machine automatically re-sets the correction amount under abest condition.

Although the preferred embodiments of the invention have been disclosedfor illustrative purposes, those skilled in the art will appreciate thatvarious modifications, additions and substitutions are possible, withoutdeparting from the scope and spirit of the invention as disclosed in theaccompanying claims.

1. A method for automatically compensating for an unbalance correctionposition and an unbalance correction amount in a balancing machine,comprising the steps of: (1-i) measuring an unbalance amount and anunbalance position of a rotor completing a primary unbalance correctionthereof; (1-ii) determining whether the initial unbalance amount beforethe unbalance correction is within the range of set value which iscorrectable by a one-time correction; (1-iii) incrementing counter if itis determined that the initial unbalance amount is within the range ofset value in step (ii); (1-iv) determining whether the unbalance amountmeasured in step (i) is larger than a good-quality reference value fordetermining whether the rotor has a bad quality or good quality; (1-v)measuring angular deviation between the unbalance positions of beforeand after the unbalance correction when the measured unbalance amount islarger than the good-quality reference value in step (1-iv); (1 -vi)determining whether the angular deviation of the unbalance positionsmeasured in step (1-v) is 0°±X1° and 180°±X1° (0<X1 <5) or 0°+X2° and180°+X2° (X1<X2 <90); and (1-vii) compensating unbalance correctionposition and amount, further comprising the steps of: (a) comparing thenumber of times when the angular deviation of the unbalance position is0°X2°and 180+X2° with the number of times when the angular deviation ofthe unbalance position is 0°−X2° and 180°−X2° when the counter from step(iii) reaches the value set by an operator for calculation of averagevalue, (b) compensating the angle for differences in angular deviationaccording to the larger number of times in step (a), (c) comparing thenumber of times when the angular deviation of the unbalance position is0°±X1° which occurs when insufficient unbalance correction is achievedat an accurate correction position with the number of times when theangular deviation of the unbalance position is 180°±X1° which occurswhen excessive unbalance correction is achieved at an accuratecorrection position, and (d) compensating for the unbalance correctionamount by increasing the unbalance correction amount if the number oftimes for 0°±X1° is larger or by reducing the unbalance correctionamount if the number of times for 180°±X1° is larger.
 2. The methodaccording to claim 1, wherein in step (1-iv), determining the quality ofthe rotor by subtracting the value optionally set to improve theaccuracy of cutting depth from the good-quality reference value for theunbalance correction.
 3. The method according to claim 1, furthercomprising the steps of: (3-i) dividing an unbalance amount range whichis measurable prior to the unbalance correction into a plurality ofsub-ranges, (3-ii) executing the steps of (1-i) to (1-vi) for each ofthe unbalance amount sub-ranges to compare the number of times when theangular deviation of the unbalance position is 0°±X1° with the number oftimes when the angular deviation of the unbalance position is 180° ±X1°,and (3-iii) re-setting an unbalance correction amount for the unbalanceamount sub-range in accordance with the higher number of times in step(3-ii).
 4. The method according to claim 1, further comprising: (4-i)displaying a current condition of the balancing machine including afinally determined unbalance position error range, a rate of productshaving a good quality, and a correction amount error; and (4-ii)automatically stopping an operation of the balancing machine inaccordance with self-determination of the balancing machine when acurrent machine condition value reaches a predetermined value at whichit is impossible for the balancing machine to operate, and warning theoperator of the current machine condition.
 5. The method according toclaim 1, wherein the compensation for the unbalance correction positionin step (1-vii) is carried out by correcting only the unbalancecorrection amount.
 6. The method according to claim 1, wherein thecompensation for the unbalance correction position in step (1-vii) iscarried out by correcting both the unbalance correction position and theunbalance correction amount based on a value obtained byvector-calculating the measured unbalance position and unbalance amount.7. The method according to claim 1, wherein the compensation for theunbalance correction position in step (1-vii) is carried out byrepeatedly performing the unbalance correction under condition in whichthe unbalance correction position is optionally shifted with referenceto 0° or 180°, storing a correction rate at every unbalance correction,calculating a maximum one of stored correction rates, and correcting theunbalance correction position based on the calculated maximum correctionrate.
 8. The method according to claim 1, further comprising: storing,as basic data, cutting data exhibiting a predetermined high correctionrate or more so that the basic data is used as recovery data whendegradation in correction rate occurs.
 9. The method according to claim8, further comprising: Automatically recovering the stored basic data ascutting data when the correction rate is reduced to a predeterminedvalue.